High-frequency transmission and reception



June l2, 1928-.

R. A. HElslNG HIGH FREQUENCY TRANSMSSION AND RECEPTION 31 1923 2 Sheets-Sheet 1 t;

ed Dec.

Ervan E N nm /m/enof Raymond/1. He/'ny .lune 12, 1928. 1,673,006

R. A. HElslNG HIGH FREQUENCY TRANSMISSION AND RECEPTION v Filed Deo. s1., 1925 2 sheets-sneer 2 /n ven for Rayma/74A.' He/ng Y REY linv duplex receiving. l

transmitter to a twofvvay` system. operatingi Patented June 12, 1928.`

l,673,00&

RAYMQNDArHEIBINGyOFMIIILBJRN,NEW J ASSIGNOR` TOIWESTERNfELEGTRICt (NINE-ANY; INCORPORATED; (1E NEW YORK, Nr Y., ACORPORATION 0F NEVI` YDRm HIGH-.EREQiUENCY-. TMNSMISSIQN AND RECEPTION\.

Application; led;ll)ember 31, `1923. Serial No. 683,630.

This invention relates.. to radio transmission and,receptlonsystems. and more particularly to. systeme using the came` antenna..

for both tranemittingand receiving.

An ohjectot' this invention is toprovide. forJ changingl Afrom` `a u tivo-.Way radio Isystem for tranemittingand receiving inaccordance with, thermethodiin which local oecillatione, used to produce an l intermedialie.` frequenty; are supplied'` bv the in accordance `with',theunethod in which the local oscillations are ,supplied byi ai local i oef cillator.

A. featureof the. invention relates tofiar! rangements whereby` an operator may swltch from full .duplex i'aclimsystem to poehv button4v or4 anteunavsivxitch t\vo-\vajv` system.. which u svstems comprlse practicallyI the same electrical elements.

A feature of the. inventolrrelatee toa.

highly` selective circuit` arrangement for amplifying: incomingvaves and suppressing, a;` particular frequency. of;undesired.waves.v

For `the purpose of, illustrating an l opera; tive system embodying the. invention it will be" hereinafter describedapplied to a system .in u which use is made :of: tl1e.sar ne.-antn na for both tranemission andvreception. A particular-f embodiment; ot' .the invention .corupriseea transmission circuit, a.l receiving circuit. and-an antenna. The transmitting circuit has,4 included therein aeourceof speech waves, a r`eource of high :frequency oscilla- `tionealndA meansfor modulating.,the high frequency Waves i by the. speech AWaves to .pro`

duce a wave for radiating. The receivingE circiiitimay be one, comprising selective am. plifying devlcee,` a.highfrecuzencyn detector ancha ,source of local. oscillationsgam mtermediate frequencyamplifier. an `internifalia te. frequencydetector. and receiverj the circuiti operating on the: basisuof double. detection or one comprising selective anliplrt'ying.,der

. vices, detectorA and receiver for single detec. tion. with an alternativecircrn-tal'iimggement` for increasing :theI range ofvselectivitvi Goin` eideration of the following4 decori ption. will suggest, `to those` Skilledwin the. art,other objects and advantages ofthe invention.

In the drawings, Fig. lirepresents avoircuit. diagram embodying the transmitter portion ofthe system.4 u

Fig. Qrepresents aioi'ni ofreceiviugi system .embodying doubleAT detectiturN Fig. 3 represents a tem embodying `single detection.

Fig. 3 represents a modification-of the high frequency amplifier and selectin cir.- cuit ofthe receivinuf` system shown `in ig; 3.

Fig. 4 'e a graphic diagram showing. the. fluctuationof amplitude with respect to frequency in a selective circuitvsuch as shown inFig. 3. i

. Figs. l and 2 together illustrate acomf plete `transrnitting and receivingsystem, Fig, l ehowing the transmitter and Fig.; 2 the. refceiver.

In Fig. 1, Waves from a. source ofuspoeC-ll` frequency Waves 1 are impressed by a .transformerr 2` upon the speech frequencyaanplir. 3.. Vacuum tube 4 represents a speech frequency modulator or variable impedance.device. Iron core choke coil 5 is connectedn. the plate` circuit `of tube 3 ando is astop ingl condenser' for preventing direct.currentiprom` beingvimpressed upon the Vgrid otftube 4. A resistance r" is located inthe positive plate supply lead from source of direct correnti l4itot` reduce the voltage impresseduponithe; lower power; tube 3. The circuit Scompriii-y ing resistance. and inductance acts as` a. stabilizing` circuit to establish the input im.-` pedanceof the tube 4,at` a proper. value.; andrprofvide aloiv resistance pathbetween. grid andvlilainent. High frequency choke, coil 9, in the` plate eircuitof tube..mothers.` impedance to high frequency` waves. and. therefore acts as a high frequency choke coil. Tube 10, in cooperation with tuned circuit.` 16, supplies oscillations which .are modulated b2 the amplified voice frequency, Waves.` Tiube 11 serves as ahigh frequencyampliter. operating in accordancerwith the constant; current method of modulating. Iron. core choke coil 12 isthespeech frequency. choke` coil ein the, constant. current modulating sys tem.Y

A` source of alternating currenitl4 supi-r plies energy to the filaments of the. tubes; 3, 4, 1() and l1. Circuit-19 acts. asianaverf age filament.potentialregulator, providi ff a potential` point corresponding to the: rn' f pointer' the filaments. The` capacitiesBO luy-pass high frequencies` around the. circuit.` 19

form of receivingv sys-A Source of direct current 14 ergy to the plates of the .tubes` 11. The armature 14 are supplies enl 3, 4, 10 fluctuations ofthe sourcei suppressed by meaneof thelterl.

which comprises a plurality of iron core choke coils and capacities.

High frequency oscillations to beat w1th incoming waves in the receiving circuit are supplied by the leads 32 and 33 which are inductively connected to the output of the oscillator 10 by means of inductance coil 15. Polarizing battery 17 is located in the grid circuit of tube 3, while battery 18 is similarly located in the grid circuit of tube 4. Choke coil 2() provides a D. C. path for current from the source 14 to the plate circuit of tube 10 and compels high frequency plate currents of the tube l() to through the tuned circuit 16. Choke coils 21, in cooperation with capacity 22, act as a filter to keep high frequency waves from entering the low frequency apparatus.

Ca acity 23 with inductance 27, offers low impe ance for high frequency Waves, and keeps the high voltage direct current from reaching the antenna. Capacity 34 is located in the antenna circuit to decrease the total antenna capacity. The circuit 29, coniprising resistance 25 and capacity 26, in combination with inductance 24 acts as a grid leak path for the grid of tube 11. Grounded air core inductance 27 has a plu rality of taps-so that the anode of tube 11 may be connected to a variable portion of the inductance of the coil.

The outgoing waves pass through the inductances 28, capacity 34, portion 35 of contact arm 38 to the antenna 39 from which they are radiated. Portions 35, 36 and 37 of contact arm 38 are insulated from each other. Trap circuit 40 comprising the inductance 41 and capacity' 42 tends to prevent the passage of carrier oscillations of'the frequency used in transmitting, but a sufficient amount passes through to be used to beat with incoming waves in one method of receiving. Switch 43 is of the double throw type making contact either with slots 44` or 45.

y Relay 46 is used to throw the contact arm 38 either to the ri ht or left by means of push-button 50 an grounded source of direct current 47. When contact arm 38 is to the left, potential from source 14 is fed to the plates of tubes 4, 1() and 11, through leads 51 and 52 and portion 37 of the contact arm. No potential is supplied to these plate circuits when the arm is to the right and, to prevent sparkingron the opening of the contacts between 37 4and leads 51 and 52, condenser 49 is connected between leads 52 and 53.

Incoming waves before reaching the detector pass through tuned circuit 54 comprising inductance 55 and variable capacity 56. Coil 57 acts as the secodnary of a transformer, the primary of which is coil 55, and in cooperation with capacity 58 of Fig. 2 constitutes a tuned circuit. The tuned circuit com rising inductance 57 and capacity 58 and t e circuit 54 are denoted by B2 and B1, respectivel They function as selective circuits for se ecting incomin waves of a specific frequency and for 'scriminating against waves of any other frequencies.

In Fig. 2, selective amplifier 59 amplifies the incoming waves selected by the tuned f circuits B, and B2. Tuned circuit A comprising inductance 60 and capacity 61 discriminates a inst oscillations of the frequency used in transmitting. Ca acity 62, and inductance 63 comprise anot er tuned circuit B, acting in cooperation with a similar circuit B, comprising inductances 64 and 65 to further select incoming waves of the frequency desired for detection.

In double detection methods of receiving, local oscillations must be supplied to the detector to beat with incoming waves. For this purpose, local oscillator 67 supplies oscillations to the high frequency detector 74 through lead 68, switch 72, induction coil 69 and inductance 64 of tuned circuit B4.

For another method of double detection, local oscillations are supplied by the transmitting system by means of leads 32 and 33, regulating device 70, which regulates the flow of high fr uency Waves to the detector tube, switch 1, induction coil 66 and inductance 64 of tuned circuit B,. hrom the last mentioned tuned circuit, B incoming waves are impressed' upon the high frequency detector 74 along with local y supplied oscillations. These oscillations and the incoming waves are combined to produce an intermediate frequency wave which passes through tuned circuit 84 comprising inductance 7 6 and capacity 75, tuned circuit 85 comprising inductance 77 and capacity 78 to t e intermediate frequency amplifier 79. The inductance coils 76 and 77 act as the prima and secondary of a transformer respectively.

The amplified waves are impressed upon intermediate frequency detector 82 through transformer 8O and the resultant audible note is detected in receiver 83. The circuit 73 comprisin resistance and capacity acts as a grid lea for tube 74, while similar circuit 81 acts in a like manner for tube 82. lVhen local oscillations are supplied by the trans mission s stem, switch 71 is closed and 72 opened. ikewise, when local oscillations are supplied b local oscillator 67, switch 72 is closed whi e 71 is opened.

Fig. 3 represents a modified form of the receiving system embodying single detection. As in VFi 2 condenser 58 acts in cooperation with in uctance 57 to complete a tuned select-ive circuit 13,. Selective amplifier 59 amplies the high frequency waves selected by tuned circuit B2 and they pass through tuned circuit A, comprising inductances 60 and 61. This circuit A, discriminates against the carrier :frequency used in transmitting,

Tuned circuit B3 comprisin inductance 63 and capacity 62 and tune circuitjB4 further select the incoming waves to be detected. The' coils .of the two circuits act as a transformer. The amplified Waves selected in this manner are further amplified by selective amplifier 86.

To prevent oscillations used in transmitting from reaching the detector, another tuned circuit A2 comprising inductance 87 and capacity 88 is placed in the output circuit of amplifier 86. Tuned circuit B5 Comprising capacity 89 and inductance 90, and similar circuit B6 com prising inductance` 91 and capacity 92 still further determine the frequency to be detected.

The selected waves are next impressed upon the detector 94 and the detected audible signal current is supplied to the receiver 95. Circuit 93 comprising resistance andcapacity actsas a grid leak for tube 94.

Fig. 3kl represents a modified circuit arrangement which may be substituted for that portion of the circuit of Fig. 3 between the dotted lines X-X and Y-Y. Inw ductance coil 99 is constructed with a num` ber of taps which cause the inductance of the coil to be variable and, in cooperation with capacity 100, makes up a tuned circuit. Inductance 101, in connection with capacity 102, forms another tuned circuit, the purpose `of which to discriminate against waves of the transmitting carrier frequency. The tuned circuit, including capacity 103 and inductance 104, coupled to the circuit including capacity 105 and inductance 106, acts in a manner similar to circuits B1, shown in Fig. 1 and B, Bm B and B in Fig. 3. By means of this arrangement, it is possible to provide ahigh degree of selectivity for the incoming carrier waves of the frequency desired for detection and to discriminate effectively against the transmitted carrier waves.

4 represents the manner in which the amplitude varies with respect to frequency at the transmitting and receiving frequency. At the frequencytransmission i. e. 650 kilo cycles the amplitude is practically zero and at frequency of reception i. e. 700 kilocycles the amplitude reaches a maximum. y

Opera'ifm/fln one method of operation employing double detection, the switch 43 makes contact with slots 44, the trap circuit 49 is cut in and spring 48 causes bar 38 to make contact to the left both for transmitting and receiving. Voice frequencyT waves from source l are amplied by amplifier 3, varied by variable impedance device 4, thereby modulating high Ifrequency oscillations from oscillator 'l0 and amplified of the frequency by high frequency amplifier 11. The high frequency amplified waves then pass through `inductances 27 and 28 and capacity 34 to the aerial 39 froinwhich they are radiated. A part ofthe transmitting carrier oscillations pass through trap circuit 40 to the receiving circuit where they are used to beat with the incoming waves.

Incomingwaves are received by antenna 39, passed through portion of contact bar 38, through condenser 34, upper slot 44, switch 43, trapcircuit and a portion 36 of a bar 38 to the two tuned circuits B, and These circuits selectthe frequency desired for detection and exclude all others.

The selected waves `are then amplified by amplifier 59 and pass through tuned circuit A `which discriminates against waves of the carrier frequency used in transmitting. They then pass through a second set of tuned circuits B, and B4, Whose design and purpose are thesame as circuits Bl and B2, previously described.

At this point, there is very little of the transmission carrier frequency Waves, because of it having been largely excluded by the circuit A. An amount of carrier fre quency energy sufficient to combine. with incoming waves to produce an intermediate frequency wave, is supplied from oscillator 10 through the leads 32 and 33, regulating device 70, and induction coil 66, which acts as a primary of a transformer the secondary of which is coil 64. Wraves of both frequencies are then impressed on a high frequency detector 74 and an intermediate frequency produced. For example. it may be assumed that transmitting is carried out at 600,000 cycles and receiving at 650,000 cycles. The resultant intermediate frequency would be 50,000 cycles. Intermediate frequency Waves pass through two tuned circuits 84 and 85, the induction coils of which act as a transformer, to the inten mediate frequency amplifier 79, where they are amplified. The amplified lwaves then pass through transformer 80 and are impressed` upon intermediate frequency detector 82. The resultant audible frequency current is supplied to receiver 83.

In a second method, also employingv double detection, the switch 43 is thrown to the right, to make contact with slots 4 5 and thereby complete the circuit of the relay 46 through push button 50. Vl'iile receiving,

the circuit through push button 50 is closed, energizing relay 46 and keeping' contact bar 38 to the right. For transmitting, the circuit through push button 50 is opened, deenergizing the relay 46, and causing bar 38 to be thrown to the left by spring 48. Modulated speech Waves are produced and radiated in a manner similar to that described in the previous method with the exception that trap circuit 40 is cut out. Incoming wves pass through portion 35 of the bar 38, through tuned circuit 34 and the rest of the system in the same manner as described before with the exception that switch 71 is opened, 7 2. is closed, and local oscillations to beat with theI incoming waves are supplied by local oscillator 67 through the leads 68. switch 72 and inductamfe coils 69 und 64.

Still another' method ot ieceiving, employing single detection, may be used in conuection with the last described method ot transmission. As before, for receiving, the circuit through push button 50 is closed. energizing the. relay 46 and throwing bor 38 to the right. Incoming waves are received by antenna 39 pass through portion 35 of the contact bar 38, tuned circuit 54 or B1, tuned circuit 2 both of which are tuned to ass only waves of the frequenc Y desired for detection, lective ampli r 59 which am lifies the -selectcd waves, circuit A1 tune to discriminate against Waves of the carrier frequency used in transmitting, tuned circuits B3 and B,i which further select the desired waves, and selective ainplier 86, which further simplifies the selected waves. These Waves then pass through the circuit A.: which functions in a manner similar to A1, tuned circuits B5 and B,s which finally select the waves to be detected. They are then impressed uon detector 94 and the resultant audible requency current is supplied to the receiver 95.

The alternative arrangement represented in 3a is used to obtain a greater degree ot selectivity by means of the variable tuned circuit comprising capacity l0() and inductance 99, inductance 99 being provided with a plurality of taps. W'aves to be detected can be more effectively selected than by the method described in connection with Fi 3.

The present .invention Iis not limite to the illustrated embodiments but may be yelnbodied in other constructions within the scope of the following claims.

What is claimed is:

1. In a radio system comprising a transmitter circuit, a receiver circuit` including tuning elements, and an antenna, a switch adapted to convert said system from one in which the transmitter and receiver are simultaneously connected to the antenna sind ,in Which incoming waves and :wa-ves of Athe carrie-r frequency used in transmitting -eaue combined to form a wave of -inteuniediate frequency for double detection to a double detection system in which the transmitter and receiver are `alternately connected to said antenna under the direct control ol a push button.

2. In a radio system comprising ,a transmitter circuit, a receiver circuit, including tuning elements, and an antenna, .a switch adapted to convent said system from one in which the transmitter and receiver are simultaneously connected to said antenna and in which incoming waves and waves of the currier frequency used in transmitting are combined to form a wave of intermediate frequency for double detection to a system in which the transmitter and receiver are alternately connected to the antenna under the control of a manually operable element operated by the operator.

3. A radio system comprising an antni. a transmitter circuit. a receiver circuit, a switch for simultaneously or alternately connecting said transmitter circuit and said receiver circuit to said antenna, selective means included in said receiver circuit coinprising a plurality of circuits resonant at the carrier frequency and usal im transmitting and a plurality of circuits resonant at the frequency of the incoming Waves to be detected whereby the amount of energy of the transmitted frequency traversing the receiving circuit is reduced.

4..1n a radio system for two-way communication comprising a transmitting lcircuit, a receiving circuit and an antenna, means for simultaneously connecting the transmitting and receiving circuits to the antenna, and means for alternately connecting the transmitting and receiving circuits to the antenna com risi 'e contact bar under the control o a y and a .push button. l

5. In a radio system for two-way communiczition. means for selectively amplifying incoming waves :for single detection comprising a plurality of ampliliers in series with a plurality of circuits resonant at the lfrequency of the incoming waves and a plurality .of circuits resonant at the carrier frequency used in transmitting, one of .each of said resonant circuits bein included in the plate circuit of each amp er.

6. In a radio system, en aerial, a transmittel' circuit. a receiver drouit, an .antenna switch adapted in one position to connect said transmitter circuit and Said receiver circuit to said aerial, a loop circuit, and another switch adapted in one position to connect said loo circuit between said aerial and said receiving circuit through a path including a contact on said antenna switch, said other switch in said one position serving to close a circuit for holding said antenna. switch in said one position and serving in another position to close a circuit whereby said antenna switch may be actuated under the control of an operator to disconnect said transmitter 4circuit from said aerial and to connect said receiver circuit thereto.

In witness whereof. I hereunto subscribe my name this 27th day of December A.. D., 1923.

RAYMOND A. HEISING. 

